<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package	Zend_Search_Lucene
 * @subpackage Search
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license	http://framework.zend.com/license/new-bsd	 New BSD License
 */


/**
 * Calculate query weights and build query scorers.
 *
 * A Weight is constructed by a query Query->createWeight().
 * The sumOfSquaredWeights() method is then called on the top-level
 * query to compute the query normalization factor Similarity->queryNorm(float).
 * This factor is then passed to normalize(float).  At this point the weighting
 * is complete.
 *
 * @category   Zend
 * @package	Zend_Search_Lucene
 * @subpackage Search
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license	http://framework.zend.com/license/new-bsd	 New BSD License
 */
abstract class Zend_Search_Lucene_Search_Weight
{
	/**
	 * Normalization factor.
	 * This value is stored only for query expanation purpose and not used in any other place
	 *
	 * @var float
	 */
	protected $_queryNorm;

	/**
	 * Weight value
	 *
	 * Weight value may be initialized in sumOfSquaredWeights() or normalize()
	 * because they both are invoked either in Query::_initWeight (for top-level query) or
	 * in corresponding methods of parent query's weights
	 *
	 * @var float
	 */
	protected $_value;


	/**
	 * The weight for this query.
	 *
	 * @return float
	 */
	public function getValue()
	{
		return $this->_value;
	}

	/**
	 * The sum of squared weights of contained query clauses.
	 *
	 * @return float
	 */
	abstract public function sumOfSquaredWeights();

	/**
	 * Assigns the query normalization factor to this.
	 *
	 * @param $norm
	 */
	abstract public function normalize($norm);
}

